The invention refers to a receiver configuration for microwave signals, including a receiving antenna, a rectifier circuit and a detector circuit.
The transmission of information in the microwave range (above 1 GHz) is made possible by a new technology which has rapidly been expanded over the past years. An introduction into integrated microwave technology is provided by the Journal "Elektronik-Anzeiger", Vol. 1977, Nos. 4, 5, 6, 8 and 9 and from the Journal "Solid State Circuits", IEEE, SC-5 (1970), December, p. 292-303.
Usually microwave signals are transmitted in a wireless fashion using special antennas and are evaluated, demodulated, mixed, amplified etc., by electronic receivers. In this context, the receiving or transmitting antennas are constructed as horn antennas, dish antennas or in planar microstrip technology. Over the past years, microstrip technology has increasingly gained a hold since miniaturized microwave solid state elements can be implemented.
This type of a strip line is formed of a conducting base plane, a dielectrical carrier material (substrate plates) above the base or ground plane and a metallized printed conductor on top of the carrier material. Characteristic impedances from 20.OMEGA. to 150.OMEGA. known from high-frequency technology can also be implemented on a ceramic substrate by choosing proper dimensions of the strip lines. The higher losses of microstrip lines as compared to coaxial or hollow waveguides, which for the most part are due to ohmic losses, to a small extent are due to dielectric losses and for non-shielded circuits are due to radiation losses, are mostly compensated for by the reduced line length. The behavior of open circuit strip lines in radiating electromagnetic waves can be utilized for the production of planar antennas. Microstrip line resonators with a line length of .lambda./2 are most frequently used.
In order to transmit various microwave signals of different frequencies, polarization and modulation, several separate receiving antennas must be provided. This is required particularly if, for example, a strong, unmodulated HF signal and a weak information signal are to be transmitted. In addition, there are difficulties in the compulsory rectifier/detector demodulation circuit. Due to the intense range of modulation of the receiver diode due to the strong, unmodulated HF signal, the sensitivity of the input circuit for a weak, modulated signal is reduced, so that an increase in the level would be required for the modulated signal.
Beginning with German Patent DE-PS 25 08 201 in which a receiving facility in an integrated construction is supplied with energy through planar antennas in strip line technology by strong microwave radiation, it is accordingly an object of the invention to provide a receiving configuration for microwave signals, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and to provide a receiver configuration with only one antenna which receives and processes two signals that are very close in frequency with strongly differing amplitudes and varying polarizations.